An asymmetric copper complex obtained by reacting an optically active salicylidene amino alcohol compound with a copper compound is useful as a catalyst for asymmetric synthesis using a diazo compound, or the like (see, patent document 1). As a method for getting out such an asymmetric copper complex in the form of crystal, there is known a method of performing a crystallization treatment in the presence of an aliphatic hydrocarbon after the complexation reaction (see, patent document 2).
[patent document 1] JP-A No. 50-24254
[patent document 2] JP-A No. 2002-241356